LONDON, England (CNN) -- British scientists are developing a tiny robot to fit inside MRI machines, which will improve the accuracy of biopsies taken to screen for prostate cancer.

Needle biopsies are currently taken from the prostate using ultrasound technology to detect where the prostate gland is.

But Dr Alex Zivanovic, of Imperial College London, told CNN that ultrasounds provided poor image quality, which makes knowing where to take the biopsy from difficult.

"Several samples are usually taken, but it's a lucky dip as to whether you've got a relevant one. The tumor could be quite small and you could miss it altogether," he said.

Zivanovic and a group of scientists at the mechatronics in medicine laboratory at the college's department of mechanical engineering are now developing a system involving magnetic resonance imaging (MRI) scanners.

The project is being funded by the National Health Service (NHS) Prostate Cancer Programme, and the machine will be developed within the next year and a half.

"MRI machines are the best way to image soft tissue inside the body, but although using MRI is preferable, to do so involves a very tight space inside the scanner tunnel. There's not much space in there, which makes it difficult," Zivanovic said.

The scientists will build a robot that will be controlled outside the scanner, while the patient will lie inside the tunnel as normal.

The MRI technology will enable them to know exactly where the biopsy needs to be taken from.

"It needs to be small enough to fit inside the tunnel but the prostate is fairly large so it needs to be able to move around," Zivanovic said. "It's a way of being more sure of catching a cancer."

He said disadvantages of using MRI included the high cost of the scanners. "But detecting more cancers early on will mean fewer patients."

Because the magnetic fields inside MRI scanners are so strong, the scientists will need to find an alternative to electricity to power the robot and ensure it can be moved around.

Piezo-ceramic actuators, or ultra sonic, technology -- similar to that used to power the zoom on some cameras -- is being investigated, he said.

Scientists at the laboratory have been researching and developing medical robots for about 15 years.

Zivanovic said the robots were able to perform high-precision tasks on a small scale.

"They're not being developed to replace surgeons, they're giving surgeons extra skills. It's about combining the advantages of robots over humans together with the advantages of humans have over robots."

Other projects at the college include a knee surgery robot, which has proved successful in clinical trials and is now being developed into a commercial product.

Another is a training system to teach surgeons how to perform knee surgery. The robot creates a "virtual" knee so that the operation can be performed in a simulated environment.

At St Mary's Hospital in London, meanwhile, robot technology was used recently to treat a patient suffering from atrial fibrillation, a common persistent heart rhythm disorder.